Organization and Summary of Significant Accounting Policies (Computation of Basic and Diluted Earnings per Share) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN	$ 55,198	$ 47,940	$ 155,365		$ 136,844
Net earnings attributable to common stockholders	46,339	39,081	128,789		110,268
Less: Earnings allocated to unvested restricted shares	(183)	(205)	(523)		(567)
Net earnings used in basic and diluted earnings per share	$ 46,156	$ 38,876	$ 128,266		$ 109,701
Weighted average number of shares outstanding	134,789,572	125,559,410	133,810,946		123,834,126
Less: Unvested restricted stock	(420,417)	(489,095)	(409,839)		(460,814)
Less: Unvested contingent shares	(476,250)	(516,249)	(451,129)		(488,952)
Weighted average number of shares outstanding used in basic earnings per share	133,892,905	124,554,066	132,949,978		122,884,360
Other dilutive securities	353,193	491,031	356,290		481,704
Weighted average number of shares outstanding used in diluted earnings per share	134,246,098	125,045,097	133,306,268		123,366,064
Series D Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	$ (4,762)	$ (4,762)	$ (14,285)	[1]	$ (14,285)	[1]
Series E Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	$ (4,097)	$ (4,097)	$ (12,291)	[1]	$ (12,291)	[1]

[1] The Series D and E preferred stock have no maturity date and will remain outstanding unless redeemed.